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參數資料
| 型號： | AD8040 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Low Power, High Speed Rail-to-Rail Input/Output Amplifier |
| 中文描述： | 低功耗，高速軌到軌輸入/輸出放大器 |
| 文件頁數： | 15/20頁 |
| 文件大?。?/td> | 649K |
| 代理商： | AD8040 |
AD8029/AD8030/AD8040
THEORY OF OPERATION
Rev. A | Page 15 of 20
03679-0-051
IN–
IN+
R
5
R
6
R
7
R
8
R
1
R
2
R
3
R
4
M
TOP
I
TAIL
M
BOT
OUTPUT
BUFFER
–V
S
R
TH
I
TH
+V
S
–1.2V
+V
S
V
OUT
Q
10
Q
11
C
MT
C
MB
–V
S
AD8029 ONLY
TO DISABLE
CIRCUITRY
DISABLE
Q
3
Q
4
Q
2
Q
1
Q
9
Q
8
Q
7
Q
6
Q
5
OUT
IN
COM
SPD
Figure 50. Simplified Schematic
The AD8029 (single), AD8030 (dual), and AD8040 (quad) are
rail-to-rail input and output amplifiers fabricated using Analog
Devices’ XFCB process. The XFCB process enables the AD8029/
AD8030/AD8040 to operate on 2.7 V to 12 V supplies with a
120 MHz bandwidth and a 60 V/μs slew rate. A simplified sche-
matic of the AD8029/AD8030/AD8040 is shown in Figure 50.
INPUT STAGE
For input common-mode voltages less than a set threshold
(1.2 V below V
CC
), the resistor degenerated PNP differential pair
(comprising Q
1
toQ
4
) carries the entire I
TAIL
current, allowing
the input voltage to go 200 mV below –V
S
. Conversely, input
common-mode voltages exceeding the same threshold cause
I
TAIL
to be routed away from the PNP differential pair and into
the NPN differential pair through transistor Q
9
. Under this
condition, the input common-mode voltage is allowed to rise
200 mV above +V
S
while still maintaining linear amplifier
behavior. The transition between these two modes of operation
leads to a sudden, temporary shift in input stage transconduc-
tance, g
m
, and dc parameters (such as the input offset voltage
V
OS
), which in turn adversely affect the distortion performance.
The SPD block shortens the duration of this transition, thus
improving the distortion performance. As shown in Figure 50,
the input differential pair is protected by a pair of two series
diodes, connected in anti-parallel, which clamp the differential
input voltage to approximately ±1.5 V.
OUTPUT STAGE
The currents derived from the PNP and NPN input differential
pairs are injected into the current mirrors M
BOT
and M
TOP
, thus
establishing a common-mode signal voltage at the input of the
output buffer.
The output buffer performs three functions:
1.
It buffers and applies the desired signal voltage to the
output devices, Q
10
and Q
11
.
2.
It senses the common-mode current level in the output
devices.
3.
It regulates the output common-mode current by
establishing a common-mode feedback loop.
The output devices Q
10
and Q
11
work in a common-emitter
configuration, and are Miller-compensated by internal
capacitors, C
MT
and C
MB
.
The output voltage compliance is set by the output devices’
collector resistance R
C
(about 25 ), and by the required load
current I
L
. For instance, a light equivalent load (5 k) allows the
output voltage to swing to within 40 mV of either rail, while
heavier loads cause this figure to deteriorate as R
C
× I
L
.
相關PDF資料 |
PDF描述 |
|---|---|
| AD8040AR | Low Power, High Speed Rail-to-Rail Input/Output Amplifier |
| AD8040AR-REEL | Low Power, High Speed Rail-to-Rail Input/Output Amplifier |
| AD8040AR-REEL7 | Low Power, High Speed Rail-to-Rail Input/Output Amplifier |
| AD8040ARU | Low Power, High Speed Rail-to-Rail Input/Output Amplifier |
| AD8040ARU-REEL7 | Low Power, High Speed Rail-to-Rail Input/Output Amplifier |
相關代理商/技術參數 |
參數描述 |
|---|---|
| AD8040AR | 制造商:Analog Devices 功能描述:OP Amp Quad GP R-R I/O 制造商:Analog Devices 功能描述:AMP QUAD LOW POWER RRI/O SMD 8040 |
| AD8040AR-EBZ | 功能描述:BOARD EVAL FOR AD8040AR RoHS:是 類別:編程器，開發系統 >> 評估板 - 運算放大器 系列:- 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:1 系列:- |
| AD8040AR-REEL | 制造商:Analog Devices 功能描述:OP Amp Quad GP R-R I/O |
| AD8040AR-REEL7 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Analog Devices 功能描述: |
| AD8040ARU | 制造商:Rochester Electronics LLC 功能描述:LOW-POWER HIGH-SPEED RAIL-TO-RAIL INPUT/OUTPUT AMPLIFIER (QU - Bulk |
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